Home appliances, power tools, space heaters, and other equipment that consume electric power are ubiquitous in society. In order to operate properly, such devices frequently rely on electrical connectors or plugs to connect to an alternating or direct current source. Such connectors frequently utilize protruding prongs of various shapes and lengths that, in use, are intended to mate with matching receiving terminals of a receptacle. Such prongs are typically supported only at one end, i.e. at the point of attachment to the plug base. They necessarily act as cantilever beams if and when they are exposed to forces or components of forces that are perpendicular to their longitudinal axes. The common two or three prong 110/120 volt alternating current plugs are examples of such connectors. They are typically used to supply AC power to various types of apparatus. Such plugs typically comprise a molded plug base with two or three protruding prongs embedded in the base on one side and a cord or cable, with two or three conductors, attached to another side of the plug base. The plug base is frequently fabricated by encapsulating the electrical connections, between the prongs and the conductors in the cord, in a plastic material to form a rugged and durable unitary piece. Typically, overmolding and/or insert molding processes are used. The 110/120 volt AC plugs, in common use in the USA, have two substantially flat or blade prongs. When plugged into a receptacle, these flat prongs act as the line voltage and neutral connections. A third prong that is substantially in the shape of a circular cylinder is typically added for safety and connects to the ground lead in a receptacle. Other types of alternating and direct current electrical connectors or plugs, that are in use worldwide, have various numbers of prongs of various shapes and purposes.
The prongs of such connectors are typically positioned and oriented as necessary to properly mate with the matching receptacles. The spacing of the prongs and the materials used in the fabrication of the plug have to be such as to avoid the excessive leakage of current and minimize the risk of a short circuit. The prongs are also sufficiently spaced from the outer edges of the plug base to reduce the chance of electrical shock and also to help maintain the physical integrity of the plug base.
Plugs, especially those utilized in a commercial or industrial environment such as, for example, a construction site, are frequently exposed to rough usage. Such plugs may be attached to, for example, the cord of an electric tool or apparatus or an extension cord. Typically the plug base and the cord are rugged enough to withstand such usage with little ill effect. When the prongs are fully engaged in a receptacle, they too are usually well protected from damage. However, when not in use, plugs are frequently left exposed, for example, on the floor of a construction site. Under such circumstances, the prongs are frequently damaged by forces that cause them to bend and twist. For example, prongs are frequently crushed when they are stepped on, run over by wheels of various pieces of equipment or hit by, for example, dropped tools or other heavy objects. They are, therefore, frequently bent and deformed. They then have to be straightened and untwisted so that they may be plugged into a receptacle.
Repeated bending and straightening is not only a nuisance, but can be dangerous. Frequently, metal prongs fatigue and break off after repeated bending. Under such circumstances, the entire cord or at least the plug needs to be replaced even though the plug base and the cord are completely sound. Even when the plug alone is replaced, it is still an added expense and a nuisance. Typically the electric cord must be cut to separate the damaged plug and the cord. The conductors in the cord have to then be stripped and attached to what are typically screw terminals in a replacement plug. Replacement plugs are typically not as rugged or robust as original injection molded plugs. Also, since they are typically installed by non-electricians, use of replacement plugs increases the risk of causing a short circuit, damaging equipment, and even causing injury or electrocution.
In certain circumstances, especially in the case where only the ground prong breaks off, the plug is used with a missing prong, which increases the likelihood of malfunction, and the danger of electrocution, personal injury or damage to equipment. Prongs that have been repeatedly bent cannot be fully straightened and as a result frequently do not fit properly in a receptacle and can damage the receptacle as well. Examples of electrical connectors are disclosed in U.S. Pat. Nos. 5,320,560 and 5,567,175, the contents of which are incorporated herein by reference in their entirety.